The Epidemiology Branch (PRP) is conducting a case-control study in Illinois and California to determine whether the use periconceptional vitamin supplements can reduce the risk of neural tube defects. Women having either a fetus or an infant with a neural tube defect have been ascertained through perinatal networks, vital records, and other sources and were matched to two controls on maternal race and geographic locale. One control is a mother with a normal pregnancy, and the other the mother of an infant with a fetus with a major health problem. Cases and controls were interviewed within 3 months of the end of pregnancy to determine whether those having a conceptus with a neural tube defect are less likely to have used vitamins in the periconceptional period. Data collection for this study is now complete. Data will be available on approximately 500 subjects in each of the three groups. We are completing record cleaning, editing and identifying the specific constituents of vitamins reportedly used by study subjects. We hope to complete this process within the next three months following which we will prepare a report of our findings for submission to a medical journal. In addition we hope, to write one or possibly more reports from the same data set regarding the epidemiology of neural tube defects and possibly other genetic syndromes associated with neural tube defects.